Drop on demand inkjet technology for producing printed images has been employed in products such as printers, multifunction products, plotters, and facsimile machines. Generally, an inkjet image is formed by selectively ejecting ink drops from a plurality of drop generators or inkjets, which are arranged in a printhead, onto an image receiving substrate. For example, the image receiving substrate may be moved relative the printhead and the inkjets may be controlled to emit ink drops at appropriate times. The timing of the inkjet activation is performed by a printhead controller, which generates firing signals that activate the inkjets to eject ink. The image receiving substrate may be an intermediate image member, such as a print drum or belt, or a print medium, such as paper. The ink ejected from the inkjets is liquid ink, such as aqueous, solvent, oil based, curable ink, or the like, which is stored in containers installed in the printer. Alternatively, the ink may be loaded in a solid or a gel form and delivered to a melting device, which heats the ink to generate liquid ink that is supplied to a printhead.
An inkjet printer is either a continuous feed inkjet printer or a cut sheet inkjet printer. Cut sheet inkjet printers form images on precut sheets of print medium, and are useful in many applications including home and office settings. Continuous feed inkjet printers form images on a continuous strip or web of print media, and are often used in applications requiring high speed and high volume printing. To prepare a continuous feed inkjet printer for printing, the continuous web is routed from a web supply along a web path through the printer. Once the continuous web reaches the end of the web path, and exits the printer, the continuous web is connected to a rewinder, which pulls the continuous web through the printer along the web path. The rewinder winds the continuous web around an output roller so that the image bearing continuous web may be transported to, for example, a finishing station in which the web may be cut or otherwise processed.
Some continuous feed inkjet printers form printed images on only a first side of the continuous web, a process referred to as a simplex printing operation. Simplex continuous feed inkjet printers have printhead assemblies with printheads that are configured to eject ink across a printing zone on the continuous web that is less than the width of the web. The printing zone is typically centered on the web with appropriate margins on each side of the printing zone. During a simplex printing operation, the continuous web makes only one pass through the printer. Specifically, the rewinder pulls the continuous web through the printer along the web path only once during a simplex printing operation.
With the addition of an external continuous web inverting system, some continuous feed inkjet printers may be configured to form printed images on a first and a second side of the continuous web. Printing images on the first and the second side of a continuous web is referred to as a duplex printing operation. In a duplex printing operation, the continuous web makes two passes through the printer, and is referred to as a half-width dual-pass duplex printing operation. In particular, the continuous web is routed from a web supply through the printer to receive ink on the first side. After the continuous web exits the printer, the continuous web is inverted by the inverting system and is then routed again through the printer to receive ink on the second side. As used herein, the term “inverted” refers to manipulation of the web to turn the web over and enable a non-printed side of the web to be presented to a printhead assembly for printing. The non-inverted and inverted portions of the continuous web are positioned on the web path as shown in the prior art printing system of FIG. 7. Specifically, FIG. 7 illustrates a top view of a roller 10 that guides the continuous web 14 along the web path in direction 16. Portion 18 of the continuous web 14 is in a non-inverted orientation as received by the printer from the web supply. Portion 22 of the continuous web 14 is in an inverted orientation as received by the printer from the inverting system. The inverted portion 22 and the non-inverted portion 18 are positioned adjacent to each other. In these printing systems, some of the printheads in a printhead assembly eject ink onto the non-inverted portion of the web and the remaining printheads in the same printhead assembly eject ink onto the inverted portion of the web. If such a printing system is operated in a simplex printing manner, then all of the printheads in the printhead assembly may be used to eject ink onto a web having a width that is slightly larger than the width of the printhead assembly. Thus, duplex printing cannot be performed on a web that is any wider than about one-half the width of the printhead assembly. Enabling duplex printing across the full width of a printhead assembly with continuous feed inkjet printers is desirable.